The multicast and broadcast service (MBS) is a promising technology to simultaneously transmit the same data content to a plurality of client devices. For example, in a wireless communication system, the wireless terminal devices are often designed and configured to receive video, audio, and multimedia content simultaneously. Therefore, the transmitter of the wireless base station will multicast or broadcast the video, audio and multimedia content to these wireless terminal devices so that each of the devices receives and presents the video and/or audio content to its user.
In addition, data packet loss or error can be unavoidable and unpredictable in the communication network, especially in a wireless communication network. In order to improve the quality of the received contents, a loss recovery technology such as Forward Error Correction (FEC) and Automatic Repeat reQuest (ARQ) can be deployed in a bi-directional communication network. The receivers are required to send back an acknowledgement reporting whether data packets have been successfully received or not. The transmitter monitors the acknowledgement (ACK), representing packets that are properly received, or negative-acknowledgment (NAK), indicating packet loss has happened. Upon reception of the feedback, the transmitter can determine whether to send out additional parity packets or re-transmit packets.
To limit the number of feedback packets from all receivers in the multicasting system, NAK instead of ACK is used to feed back to the sender because of its lighter overhead requirement. However, for a multicast or broadcast service, the transmitter may send the same data packets to dozens or hundreds of receivers and since the report of NAK packets is also not predictable, data congestion can still occur in a reverse uplink channel.
US2008/0031179 discloses a method to assign a feedback time slot to all receivers with a predetermined number of packet losses in time division multiplexing accessing mode. For example, receivers having experienced one packet loss will send feedback in the first time slot, receivers sending feedback in the second time slot will have experienced two packets losses. The required feedback bandwidth depends on the number of packet losses. The drawback of this method is that the transmitter should allocate an estimated number of time-slots (equal to the maximum number of packet losses) for the feedback transmission.
Therefore, an improved method for receiving and transmitting data contents is needed.